(a) Field of the Invention
This application relates to a device and method for connecting sections of tubing used in underground sprinkler systems. More particularly, but not by way of limitation, to a telescoping coupler that includes a threaded portion that is used to extend the coupler in order to drive the ends of the coupler into the open ends of the sections of partially-buried tubing to be joined.
(b) Discussion of Known Art
For the reasons discussed in my U.S. Pat. Nos. 5,624,139 and 5,403,046, both of which are incorporated herein by reference in their entirety, polyethylene is widely used for the tubing or ducts that are used in forming underground sprinkler systems. The polyethylene tubing is tough and relatively stiff, so that it will not collapse due to the weight of the soil used to backfill the trench used to lay out the sprinkler system. The stiffness of the polyethylene tubing, however, creates problems whenever it is necessary to join two lengths or sections of polyethylene tube or hose. Often, the need to join sections presents itself when a section of the tubing or hose has developed a leak, such a leak from a hole caused by water that has been allowed to freeze in the tubing, or by mechanical damage caused while digging around the sprinkler system. To repair the leak, the damaged section must be removed, and the two remaining sections joined.
One common type of device for joining sections of tubing includes one-piece couplers such as the type disclosed in U.S. Pat. No. 1,996,855 to Cheswright. The use of types of couplers for joining sections of polyethylene tubing is common, but often leads to further damage to the tubing. This damage includes kinking sections of the tubing, with the kink creating a weakened section in the tubing, and significant distortions to the ends and inner diameter of the sections to be joined, such that inner diameter is enlarged to the point where a water-tight seal cannot be achieved. Many of the problems associated with making connections with devices such as the Cheswright device stem from the fact that to install the coupling, the installer very frequently has to insert the fitting into the first section of tubing, and then lift and try to gently bend the tubing in order to shorten that length of tubing enough to insert the remaining end of the fitting into the second section of tubing. Even if due care is exercised in the installation, while so bending the hose it often kinks, which substantially weakens the integrity of polyethylene hose. This in turn is likely to lead to future failures of the system.
My U.S. Pat. Nos. 5,624,139 and 5,403,046 solved the problems associated with the limited space between the sections of tubing, and thus greatly reduced, if not eliminated, the need to bend the tubing in order to install a fitting that would join two sections. My solutions disclosed in these patents solve the problems associated with space between the sections to be joined, but through years of use in the field it was discovered that it is often very difficult to insert the ends, or nipples, of the fittings into the polyethylene tubing sections to be joined. This problem is inherent to the repair of polyethylene tubing, simply due to the toughness and stiffness of polyethylene tubing.
Still further, an efficient mechanism for joining the components of the disclosed invention without using chemical solvents or ultrasonic welding is also needed.
Therefore, a review of known devices reveals that there remains a need for a simple device that facilitates the insertion of fittings used connect a pair of sections of polyethylene tubing that are partially buried.